SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '340ec8ad3e9f126e483e4f75595bb406d13d958116020d209bf693ddfb17c308' 
  AND token = 'U6G8aTFbKFDTQBAlRKd5IPoNT0TQY7Lr9D3waH83OXw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}